He was in Justice League Task Force for a 2 issue series both of which ARE on DCU at the moment. So should check those out. As well as in Legends which is on here (although she shared that space with a LOT of other heroes obviously)
Most notably his post-Rebirth appearances include Batman (2016) 9,11,13,16,17,20 which are also all on here (apparently he was also in issue 56)
I looked up some appearances of the character. He first appeared in Richard Dragon Kung-Fu Figher #1 in the 70’s and many issues after that, but they are not on here and I checked and they are not on Comixology either. So if you even want to go that far back you would have to go on Amazon or check back issue bins. He was however also in the 2005 Richard Dragon series issues 1-8, not here or on Comixology but would probably be easier to track down.
He was also in some Detective Comics in the 70’s but again not on Comixology, here or reprinted anywhere that I know of so short of hunting down the original issues no real way tor read them now.
He was in issue’s 3-5 of the 1998 Hawk and Dove series.
Also in some issues of the second Justice League of America series.
Post New-52 he is in Deathstroke’s first five issues
Also in Red Hood and the Outlaws 22-26
Hope that helps.